Swine flu has spread in Mexico, killing more than 100 people, while non-fatal cases have also been detected in Canada and the US. Mexico City residents are wearing surgical masks to prevent infection spreading.
A procession of Christ of the Health was held in Mexico City's Metropolitan Cathedral as the country's president urged calm.
Health workers in Mexico screened travellers at bus stations and airports for symptoms.
The US has declared a public health emergency. Tests were being carried out at a San Diego lab. The World Health Organization warned that the outbreak could become a pandemic.
Suspected cases were detected in a group of students from Rangitoto College in Auckland, the largest city in New Zealand, after they returned from a trip to Mexico.
Throughout the world, government health agencies were keeping an eye on passengers arriving by air. At Bali international airport, a computer screen shows images of people scanned for high temperatures.
In Taiwan, a government animal agency worker disinfects pigs as a precautionary measure. The disease usually occurs in humans who have close contact with pigs, but human-to-human transmission is rare.
The World Health Organization said there was no evidence to link exposure to pork with infection. However, products were being examined in South Korea, and Russia and China have banned Mexican pork imports.
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